Fuel tank level detector and shut-off valve

Abstract

A system for controlling the liquid level in a tank such as a fuel tank. The system includes a main inlet valve and a jet level sensor mechanism. Redundant relay valves which are fluid-pressure responsive are interconnected between the inlet valve and the jet level sensor to cause the inlet valve to shut off when the fluid within the tank reaches a pre-determined level. The inlet of the jet level sensor is connected through a pair of shut-off valves to the inlet valve to thus provide a source of liquid to flow through the jet level sensor. The shut-off valves are connected to be responsive to an over pressure condition which might exist in the tank which is being filled or an over pressure condition at the inlet resultant from excessive fluid pressure at the source thereof. The liquid level control system is modularized by providing a plurality of plate members formed of molded plastic. Each of the plate members is constructed in such a way as to provide the various porting and interconnection between the valves and the jets. A common diaphragm member is utilized for each of the pressure-responsive valves with one side of the diaphragm being connected in the case of each of the valves to a different fluid pressure source for operation thereof.

What is claimed is: 
     
       1. A liquid level control system for disposition in a tank and for use in automatically shutting off liquid flow when a desired liquid level in said tank has been reached, said system comprising: a. inlet valve means coupled to said tank to receive liquid under pressure from a source thereof, said inlet valve means being normally closed and opened responsive to said liquid under pressure thereby to provide liquid flow through said inlet valve means directly into said tank, said inlet valve means also having means responsive to a flow of liquid in a predetermined direction to close said inlet valve means:   b. jet level sensing means having an input and an output for detecting the level of liquid in a tank, said jet level sensing means including   
     
     
       1. ejector means for providing liquid flow into said tank, 2. receiver means spaced from said ejector means and aligned to receive said liquid flow from said ejector means thereby to provide an output liquid pressure signal from said jet level sensing means when the liquid level in said tank is below a pre-determined level, said output signal being interrupted when the liquid level in said tank is at said pre-determined level;   c. means connecting said inlet valve means to said jet level sensing means to supply a flow of liquid to the input of said jet level sensing means;   d. first pressure responsive valve means connected between said output of said jet level sensing means and said inlet valve, said valve means being movable from a first position into a second position responsive to said output liquid pressure signal from said jet level sensing means, and includes means to retain said valve in said first position in the absence of said output liquid pressure signal, said connection between said first valve means and said inlet valve providing flow of liquid from said source, through said first valve means when in said first position, and to said inlet valve to close said means responsive to a flow of liquid in a predetermined direction of said inlet valve; and   e. second pressure responsive valve means disposed in said connecting means, said second valve means being movable from a first position to a second position responsive to a predetermined liquid pressure in said tank and includes means to retain said second valve means in said first position in the absence of said predetermined pressure in said tank, said second valve means when in said second position interrupting the liquid flow to said jet level sensing means thereby precluding liquid leakage into said tank through said jet level sensing means.   
     
     
       2. Liquid level control system as defined in claim 1 wherein said second pressure responsive valve means is connected to said inlet valve means and is responsive to over-pressure in said tank. 
     
     
       3. Liquid level control system as defined in claim 1 wherein said first and second pressure responsive valve means are diaphragm valves having a common member providing the diaphragm, for each of said valves. 
     
     
       4. Liquid level control system as defined in claim 1 wherein said jet level sensing means includes first and second jets, each having an ejector and a receiver, and said first pressure responsive valve means includes first and second diaphragm valves connected to the receivers of said first and second jets respectively. 
     
     
       5. Liquid level control system as defined in claim 1 wherein said connecting means includes a restriction orifice to control the pressure of liquid applied to said jet level sensing means. 
     
     
       6. Liquid level control system as defined in claim 1 wherein said first and second pressure responsive valve means includes a plurality of molded plastic plates stacked one on the other, each of said plates have opposed major faces. 
     
     
       7. Liquid level control system as defined in claim 6 which further includes common diaphragm means for said first and second pressure responsive valve means, said diaphragm means being secured between adjacent plates. 
     
     
       8. Liquid level control system as defined in claim 6 which further includes a base and means securing said plates to said base. 
     
     
       9. Liquid level control system as defined in claim 6 wherein selected ones of said molded plastic plates include sealing beads formed integrally with one major face thereof. 
     
     
       10. Liquid level control system as defined in claim 6 wherein selected ones of said plates define recesses in a major face thereof and selected other of said plates include protrusions extending from a major face thereof, said protrusions seating within said recesses when said plates are assembled with said major faces in opposed relationship to align said plates. 
     
     
       11. Liquid level control system as defined in claim 6 wherein selected ones of said plates define aligned openings therethrough and which further include alignment securing means extending through said openings to align said plates. 
     
     
       12. Liquid level control system as defined in claim 11 wherein said alignment securing means is a portion of said jet level sensing means. 
     
     
       13. Liquid level control system as defined in claim 1 wherein said jet level sensing means includes two jet ejectors and two jet receivers, each one of said ejectors being axially aligned with one of said receivers to provide redundant level sensing. 
     
     
       14. Liquid level control system as defined in claim 1 wherein said inlet valve means includes first and second poppet means each separately operable to effect closure of said inlet valve means.